How Can Dandruff With Dead Skin Be Treated?

sir, I request to you that please give me appropriate suggestions sir i am 24, and i share my problem with you, sir i have problem of dandruff for so many years. it is a regular problem increases according to the season sir the problem is like that some times the dead skin comes out from my head the skin is between the hair, sir sometimes the powder comes out from my head and some times the eggs looks like dandruff comes out, sir i have a bad habit that most of the times i rub my head skin from my nails and this cause the powder comes out from my hair sir i have changed so many shampoos and now a days iam not using any type of hair oil, sir kindly suggest me that what can i do for my hair because my hair growth is very poor and my hair is also fall, sir suggest me best medicine, shampoos, hair oil etc.